Answer : The percent error caused by this mistake is, 0.73%
Solution : Given,
Actual volume = 21.86 ml
Measured volume = 21.7 ml
Formula used for percent error :
![\%\text{ Error}=\frac{(\text{Actual volume}-\text{Measured volume})}{\text{Actual volume}}* 100](https://img.qammunity.org/2020/formulas/chemistry/high-school/cxu4x4256fou3r62yeyohlhzol2i1cfnt0.png)
Now put all the values in this formula, we get the percent error.
![\%\text{ Error}=((21.86-21.7)ml)/(21.86ml)* 100=0.73\%](https://img.qammunity.org/2020/formulas/chemistry/high-school/5rqd9wqanyddeo2annuh4lltx702yaamat.png)
Therefore, the percent error caused by this mistake is, 0.73%